Technical Field
The present invention relates to a compressed powder core with excellent magnetic properties, powders for the compressed powder core, and a method for producing the compressed powder core.
Background Art
Conventionally, reactors have been used for hybrid vehicles, electric vehicles, photovoltaic power generating systems, and the like. Such reactors adopt a structure in which a coil is wound around a ring-shaped core that is a compressed powder core. When such a reactor is used, a magnetic field of at least 40 kA/m is applied to the core to flow a wide range of current through the coil. Even under such an environment, it is necessary to stably secure the inductance of the reactor.
In view of the forgoing, a reactor 9 illustrated in FIG. 13A has been proposed, for example (see Patent Document 1, for example). The reactor 9 has a ring-shaped core (i.e., compressed powder core) 91 that are split in two, gaps 93 provided between the split cores 92A and 92B, and coils 95A and 95B wound around portions of the core 91 including the gaps 93.
According to such a reactor 9, as the gaps 93 are provided between the split cores 92A and 92B, even when a wide range of current is flowed through the coils 95A and 95B of the reactor 9, it is possible to secure a stable inductance in such a current range.
By the way, compressed powder cores are also used for choking coils, inductors, and the like. As such compressed powder cores, a compressed powder core is disclosed that satisfies, provided that the initial permeability is μ0 and the permeability when a magnetic field of 24 kA/m is applied is a relationship of μ/μ0≥0.5 between μ0 and μ (see Patent Document 2, for example). According to such a compressed powder core, it is possible to suppress a decrease in the permeability of the compressed powder core even when a high magnetic field is applied thereto.